Tompkins, 37, died in his sleep Sunday. An autopsy was performed Monday and while results are not yet available, Stout, who is also one of Tompkins UFC fighters, says it was a heart attack.

"I don't know what to say," Stout says. "It's not supposed to happen to a healthy 37-year-old person. Who would think he had to get checked out for that?"

The funeral service is Friday at 1 p.m. at West Park Church, 955 Gainsborough Rd., London.

A spokesperson for the Oxford detachment of the OPP said Tompkins' death was "not suspicious."

He died at a friend's house in Ingersoll.

"Shawn's family had a history of heart disease," said Tompkins' manager Gary Ibarra of Athletic Management & Representation Group (AMR).

"Shawn had an enlarged heart and blocked arteries," Ibarra said. "No one had any idea.

"It really doesn't matter how much you exercise and what kind of shape you are in. That's why everyone is in such shock."

Tompkins was AMR's second client and Ibarra said he was probably the most important at the time because it gave his company legitimacy.

"But that's secondary," he said. "Shawn had become a friend."

The closely knit local MMA community is still reeling over the sudden death. Even though Tompkins was based in Las Vegas his career began in Tillsonburg and London and several current fighters have been with him since they were young.

"Losing Shawn is like losing a brother, a . . . I just don't know what to say," said Stout, Emilie Tompkins' brother.

Stout, fellow UFC fighter Mark Hominick and Chris Horodecki are involved in the Adrenaline Training Centre, a gym that was spawned by Tompkins' development of an MMA-based gym in London. Adrenaline will be closed until Monday.

Stout said everyone associated with Tompkins is still in shock.

"You start thinking and you just don't know where you go from here?" Stout said. "What do we do? Right now where just trying to get through everything."